quicksilver 0.3.2

/// The current state of a button
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
#[repr(u8)]
pub enum ButtonState {
    /// The button was activated this frame
    Pressed = 0,
    /// The button is active but was not activated this frame
    Held = 1,
    /// The button was released this frame
    Released = 2,
    /// The button is not active but was not released this frame
    NotPressed = 3,
}

impl ButtonState {
    pub(crate) fn update(&self, new: ButtonState) -> ButtonState {
        match (self.is_down(), new.is_down()) {
            (false, false) => ButtonState::NotPressed,
            (false, true) => ButtonState::Pressed,
            (true, false) => ButtonState::Released,
            (true, true) => ButtonState::Held
        }
    }

    /// Determine if the button is either Pressed or Held
    pub fn is_down(&self) -> bool {
        match *self {
            ButtonState::Pressed | ButtonState::Held => true,
            ButtonState::Released | ButtonState::NotPressed => false,
        }
    }

    /// Convert the button from a temporary state to a permanent state
    ///
    /// Pressed states become Held, Released states become NotPressed
    #[must_use]
    pub fn clear_temporary(&self) -> ButtonState {
        if self.is_down() {
            ButtonState::Held
        } else {
            ButtonState::NotPressed
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn clear_temporary() {
        for button in [ButtonState::Pressed, ButtonState::Held, ButtonState::Released, ButtonState::NotPressed].iter() {
            assert_eq!(button.is_down(), button.clear_temporary().is_down());
        }
    }
}